The present invention relates to the entrapment and isolation of free thermal neutrons within the hollow cage-like structure of fullerenes.
Fullerenes are large molecules of carbon in the form of a hollow geodesic dome containing 32 to several hundred carbon atoms. Fullerenes containing 60 carbons (C60), better known as Buckminsterfullerene or “buckyballs,” are extremely stable. The C60 fullerene has an icosohedral symmetry consisting of 12 five-numbered rings and 20 six-membered rings and resembles the patchwork faces of a soccer ball. Another fullerene (C70) which is also very stable contains 25 six-membered rings and has a shape resembling a rugby ball.
Studies of fullerenes indicate that this material exhibits a remarkable range of physical and chemical properties. For example, fullerenes have high thermal and mechanical stability, and have been generated with atoms other than carbon replacing some of the carbon atoms in the cage structure itself. Fullerenes also exhibit regenerative properties so that, in the event of a rupture in the molecule, it will reclose.
Free neutrons, while relatively easy to produce and even isolate, are extremely difficult, if not impossible to trap and store in significant numbers for use outside the neutron generator. Neutrons are subatomic particles belonging to the class called baryons. They have a rest mass of 1.009 atomic mass units (AMU) and no electric charge. Neutrons are a constituent of the nucleus of all atoms except simple hydrogen, the number of neutrons present being the difference between the mass number and the atomic number of the element. Neutrons may be liberated from the nucleus of various elements, particularly uranium-235 and plutonium-239. They can also be produced by bombardment of other elements, e.g., beryllium, with charged particles.
High energy neutrons such as those emitted by the fission of a uranium-235 nucleus in a nuclear reactor are called “fast” neutrons. In the reactor these fast neutrons are slowed down by collisions with the nuclei of the atoms of the reactor's moderator, typically, water or graphite. When a sufficient number of collisions have slowed the neutrons to an energy equal to the thermal energy of the moderator, the neutrons are called “thermal” neutrons.
While various atoms and ions have been encapsulated within a fullerene cage, there are no known procedures for encapsulating neutrons within a fullerene molecule.
The only previously known procedure for trapping free neutrons is a method in which a small number of neutrons are trapped using a specially designed neutron trap operating near absolute zero temperature. The very small number of neutrons and the extremely low temperature requirement severely restrict the ability to use this method for other than very limited scientific investigation. There is no known procedure for trapping and isolating neutrons within a molecule. Accordingly, there exists a need to be able to easily and economically trap and store free thermal neutrons for use in other applications such as scientific, medical and engineering, to name a few, at a location away from the interior of a nuclear reactor or other neutron generator.